Using the sunspot cycle to date ice cores

Abstract

For many ice cores, the snow accumulation rate is too low to preserve annual stratigraphy, precluding direct measurement of annual layer thickness. For selected Holocene sections of the Taylor Dome core, East Antarctica, we instead use high‐resolution 10Be measurements to establish a nominal 11‐year thickness, taking advantage of the solar cycle in cosmogenic isotope production. We compare measured thicknesses with the layer thickness profile predicted by a finite element ice flow model. The results are in good agreement, supporting the assumption that the length of the solar cycle has remained essentially constant throughout the Holocene. For ice cores where annual layers are not preserved, the 10Be 11‐year layer method can be used as an independent check on flow‐model estimates of layer thickness and to estimate past accumulation rates. It should be possible to accurately date ice cores by counting 11‐year layers detected with continuous high‐resolution 10Be measurements.